rich this is a very common problem with d.i.y lighting, unfortunately you do need the terminal block as i pressume that the connections are part of the loop system for lighting in other rooms.
did the fan used to come on when you turned on the light or is it an independant pullcord or switch?
anyway, you will need to keep the terminal block, in the terminal block you will have a lot of black or blue wires connected together connect the blue from the new fitting to them and earth to earth, now the "hard bit" one of the terminals in the terminal block will have a lone black or blue wire that should have a red or brown piece of tape or sleeving on it, or if the fan comes on when you flick on the light switch then there will be a piece of terminal block with what looks like a N+L together, but the N (the black or blue that should be marked with brown or red tape or sleeving) is actually the live coming back up from the switch, connect your brown from the new light to this and you should be fine,
so unfortunately you do have to try and accomodate the terminal block, somehow!
stoozybhoy, February 2010